The BMW M5 5.0 V8 400hp (E39 - 1995 - 2003) produces 400bhp and 500Nm in standard form. Our Stage 1 ECU tuning file raises output to 430bhp and 535Nm, a gain of 30bhp and 35Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.